The present invention relates to a lock mechanism designed for mortise mounting in a door frame, stile or jamb, and more particularly to a novel design for a lock mechanism which enables the mechanism to be accommodated in a casing of relatively narrow depth, such that the mechanism can be mortise mounted in modern, narrow door stiles or frames without the need for the provision of special pockets to accommodate the lock casing.
The basic structural elements of the numerous prior art type security locks available do not vary widely, nor does the design of these locks, examples of which are illustrated in U.S. Pat. Nos. 3,999,411; 2,800,347; 2,032,765, and 1,569,228. Basically, all of these prior art designs utilize a retractable latch bolt; one or more separately actuated operating mechanisms, viz. handles, solenoid, or key cylinders, for effecting retraction of the latch bolt; and some form of deadlock mechanism which prevents unauthorized retraction of the latch bolt when the door is in the closed condition. With regard to the latter point, when the door is in the closed or locked condition, retraction of the latch bolt can be accomplished only by way of the provided operating mechanism, with the deadlock mechanism preventing the bolt from being retracted by use of tools or other unauthorized devices.
The prior art designs are such that they require a rather deep casing structure to accommodate the various linkages, levers and operating means which must be housed therein. While these prior art designs have proven satisfactory for conventional door installation, where unlimited depth for mortise of the lock casing is available, the introduction and use by architects of modern door frames and stiles of relatively narrow width has brought to light a severe deficiency in these prior art designs. More specifically, these modern frames or stiles are too narrow to accommodate the deep casing structure or the prior art locks, and if these locks are used, the casings must be modified. As such, a need exists for a lock design that can be accommodated within a narrow or shallow casing structure such that the overall mechanism can be mounted in a narrow stile or door frame without the need for special pockets or modifications. As will become apparent from the discussion to follow with respect to the drawings, the present invention provides a lock construction which fits this need. More specifically, while the lock mechanism of the present invention incorporates the standard structural elements, viz., latch bolt, deadlock and operating mechanism, these elements have been designed and mounted in such a manner that the necessary movement required in the function of the lock is accommodated in a minimum amount of space. Also this design reduces the number of separate components and generally simplifies the overall design, all of which results in a more dependable lock mechanism, without sacrifice of the dependability and strength of the lock. Other advantages and features of the invention will become apparent from the following description of the drawings and discussion of the preferred embodiments of the invention illustrated therein.